The present invention relates to a control valve for a variable capacity compressor to be employed in air conditioners for vehicles, etc., and in particular to a control valve for a variable capacity compressor, which is designed to supply, upon requirements, a coolant gas from a discharge pressure region to an intermediate pressure region.
A variable capacity compressor is generally provided with a cylinder, a piston, a wobble plate, etc., and is employed for compressing and discharging a coolant gas in an air conditioner of vehicles. There is known a variable capacity compressor comprising a coolant gas passage for communicating a discharge pressure region with a crankcase, and designed such that the quantity of coolant gas to be discharged can be changed in conformity with changes in inclination angle of the wobble plate which can be effected through an adjustment of the pressure inside the crankcase. The adjustment of pressure inside the crankcase is performed by feeding a high pressure compressed coolant gas from the discharge pressure region to the crankcase while adjusting the opening degree of a control valve disposed at an intermediate portion of the coolant gas passage.
As one example of the aforementioned control valve, a control valve 100xe2x80x2 for a variable capacity compressor (hereinafter referred to simply as a control valve) as shown in FIG. 8 is known (see Japanese Patent Unexamined Publication (Kokai) H11-218078). This control valve 100xe2x80x2 is disposed neighboring on the rear housing 3 of the variable capacity compressor 1 and is airtightly placed inside space 84 of the rear housing 3, the airtightness thereof being effected by means of O-rings 121axe2x80x2, 121bxe2x80x2 and 131bxe2x80x2. 
As shown in FIG. 8, this control valve 100 xe2x80x2 is constituted by a main body 120xe2x80x2, solenoid magnetization portion 130xe2x80x2 and pressure sensitive portion 145xe2x80x2, wherein the solenoid magnetization portion 130xe2x80x2 is disposed at the center, and the main body 120xe2x80x2 and pressure sensitive portion 145xe2x80x2 are respectively disposed on both sides of the solenoid magnetization portion 130xe2x80x2.
The solenoid magnetization portion 130xe2x80x2 is provided on the outer circumference thereof with a solenoid housing 131xe2x80x2, in which a solenoid 131Axe2x80x2, a plunger 133xe2x80x2 to be moved up and down by the magnetization of solenoid 131Axe2x80x2, and a suction member 141xe2x80x2 are housed. A plunger chamber 130axe2x80x2 housing the plunger 133xe2x80x2 is communicated with suction coolant port 129xe2x80x2 attached to the main body 120xe2x80x2.
The pressure sensitive portion 145xe2x80x2 is disposed below the solenoid housing 131xe2x80x2 and is provided therein with pressure sensitive chamber 145axe2x80x2, in which a bellows 146xe2x80x2 and a spring 159xe2x80x2 which are designed to actuate plunger 133xe2x80x2 via a stem 138xe2x80x2 are positioned.
The main body 120xe2x80x2 is provided with valve chamber 123xe2x80x2, and a ball valve 132xe2x80x2 to be actuated by the plunger 133xe2x80x2 through a push rod 135xe2x80x2 is disposed inside the valve chamber 123xe2x80x2, to which a coolant gas of high discharge pressure Pd is designed to be introduced. The valve chamber 123xe2x80x2 is provided at the bottom surface thereof with a valve bore 125xe2x80x2 communicating with a crankcase coolant port 128xe2x80x2, and the upper space of the valve chamber 123xe2x80x2 is closed by means of a stopper 124xe2x80x2. This stopper 124xe2x80x2 is provided at the central portion thereof with a discharging coolant-introducing port 126axe2x80x2 and also provided at the bottom portion thereof with valve-closing spring 127xe2x80x2 for urging the valve 132xe2x80x2 to move toward the bottom side of the valve chamber 123xe2x80x2.
The main body 120xe2x80x2 is further provided with a port 114xe2x80x2 which is communicated via a passageway 57 with a crankcase constituting an intermediate pressure region of the compressor 1 and also with a chamber pressure Pc of the crankcase. Therefore, when the valve bore 125xe2x80x2 is opened by means of the valve 132xe2x80x2, a high-pressure coolant gas that has been introduced into the valve chamber 123xe2x80x2 is allowed to be introduced via the port 114xe2x80x2 and the passageway 57 into crankcase. The suction coolant port 129xe2x80x2 which is communicated via a passageway 80 with a suction pressure region of the compressor 1 and is designed to receive a suction pressure Ps of the suction pressure region is not only communicated with the pressure sensitive chamber 145axe2x80x2, but also communicated with a suction pressure-introducing space 85 formed between the rear housing 3 and the solenoid housing 131xe2x80x2.
The plunger 133xe2x80x2 disposed inside the solenoid housing 131xe2x80x2 is slidably sustained by a pipe 136xe2x80x2, which is air-tightly contacted via a couple of O-rings 134axe2x80x2 and 134bxe2x80x2 with one end of the main body 120xe2x80x2. Further, a valve-opening spring 144xe2x80x2 for urging the plunger 133xe2x80x2 to move away from the suction member 141xe2x80x2 is interposed between the plunger 133xe2x80x2 and the suction member 141xe2x80x2. Out of a pair of stoppers 147xe2x80x2 and 148xe2x80x2 disposed inside the bellows 146xe2x80x2 arranged inside pressure sensitive chamber 145axe2x80x2, only the stopper 147xe2x80x2 is attached to the lower end 138bxe2x80x2 of the stem 138xe2x80x2, thereby enabling the stopper 147xe2x80x2 to move close to or away from the stopper 148xe2x80x2. Additionally, a spring 150xe2x80x2 for urging the stopper 147xe2x80x2 to move away from the suction member 141xe2x80x2 is interposed between the stopper 147xe2x80x2 and the suction member 141xe2x80x2.
The pipe 154xe2x80x2 functions to form the pressure sensitive chamber 145axe2x80x2 and is air-tightly secured via an 0-ring 156xe2x80x2 to the solenoid housing 131xe2x80x2, and an adjusting screw holder 152xe2x80x2 is fixedly fitted in this pipe 154xe2x80x2. This adjusting screw holder 152xe2x80x2 is provided therein an adjusting screw 156xe2x80x2 for adjusting the strength of the bellows 146xe2x80x2. The adjusting screw 156xe2x80x2 is air-tightly contacted via an 0-ring 157xe2x80x2 with the adjusting screw holder 152xe2x80x2 and the distal end thereof is contacted with the stopper 148xe2x80x2 of the bellows 146xe2x80x2.
By the way, a cord 158xe2x80x2 for supplying a predetermined magnetization current that will be controlled by a controlling computer (not shown) is connected with the solenoid 131Axe2x80x2.
When solenoid 131Axe2x80x2 of control valve 100xe2x80x2 is magnetized, the plunger 133xe2x80x2 is pulled toward the suction member 141xe2x80x2 against the urging force of the valve-opening spring 144xe2x80x2, thereby causing the push rod 135xe2x80x2 connected with the plunger 133xe2x80x2 to move. As a result, the valve 132xe2x80x2 is moved in the direction to close the valve bore 125xe2x80x2 of the main body 120xe2x80x2. When the suction pressure Ps inside the pressure sensitive chamber 145axe2x80x2 becomes higher, bellows 146xe2x80x2 is forced to contract in conformity with the suction pressure Ps, so that the direction of this shrinkage becomes identical with the sucking direction of the plunger 133xe2x80x2 to be effected by the solenoid 131Axe2x80x2. This displacement of bellows 146xe2x80x2 is followed by the valve 132xe2x80x2, thereby reducing the opening degree of the valve bore 125xe2x80x2. As a result, the quantity of high-pressure coolant gas to be introduced into the crankcase through the port 114xe2x80x2 and passageway 57 after being introduced into the interior of the valve chamber 123xe2x80x2 via the discharging coolant-introducing port 126axe2x80x2 from the discharge pressure region is caused to decrease (crankcase pressure Pc is lowered), thereby increasing the angle of inclination of the wobble plate of the compressor 1. Whereas, when the suction pressure Ps inside the pressure sensitive chamber 145axe2x80x2 becomes lower, bellows 146xe2x80x2 is forced to expand due to a spring 159xe2x80x2 and also to the restoring force of the bellows itself, so that due to the displacement of the bellows 146xe2x80x2, the valve 132xe2x80x2 is pushed by the stem 138xe2x80x2 and the plunger 133xe2x80x2, thereby causing the valve 132xe2x80x2 to move in the direction to increase the opening degree of the valve bore 125xe2x80x2. As a result, the quantity of high-pressure coolant gas to be introduced into the crankcase from the passageway 57 through the port 114xe2x80x2 and after being introduced into the interior of the valve chamber 123xe2x80x2 via the stopper 124xe2x80x2 from the discharge pressure region is caused to increase (crankcase pressure Pc is raised), thereby decreasing the angle of inclination of the wobble plate.
On the other hand, when the solenoid 131Axe2x80x2 is demagnetized, the pulling of the plunger 133xe2x80x2 toward suction member 141xe2x80x2 is diminished, so that due to the urging force of the valve-opening spring 144xe2x80x2, the plunger 133xe2x80x2 is caused to move in the direction away from the suction member 141xe2x80x2, thereby causing the valve 132xe2x80x2 to move, through the push rod 135xe2x80x2, in the direction to open the valve bore 125xe2x80x2 of the main body 120xe2x80x2.
By the way, the aforementioned conventional control valve 100xe2x80x2 is constructed such that as shown in FIG. 8, a low temperature coolant gas that has been introduced into the pressure sensitive chamber 145axe2x80x2 of the main body 120xe2x80x2 from the suction pressure region is then introduced into the suction pressure-introducing space 85 interposed between the solenoid housing 131xe2x80x2 and the rear housing 3. In this case, since the suction pressure-introducing space 85 is air-tightly closed through the O-ring 131bxe2x80x2 placed on the sidewall of the solenoid housing 131xe2x80x2, the sidewall of the solenoid housing 131xe2x80x2 can be cooled entirely, so that the temperature of solenoid 131Axe2x80x2 inside the solenoid housing 131xe2x80x2 can be suppressed from being raised, thus making it possible to suppress the deterioration of magnetization force.
However, for the purpose of enabling a difference in pressure between a high discharging pressure and an intermediate pressure to be effectively utilized by the compressor 1, it is required to introduce the aforementioned high discharge pressure Pd not only into the crankcase constituting a first intermediate pressure region but also into a second intermediate pressure region constituting another intermediate pressure region. However, the aforementioned conventional control valve 100xe2x80x2 is suited for securing this second intermediate pressure Pcxe2x80x2.
With a view to overcome the aforementioned problems, the present inventors have already proposed various kinds of invention on a control valve for a variable capacity compressor (for example, Japanese Patent Application H10-295492 and H10-367979). However, any particular consideration is not taken into account in these control valves on the idea that a discharge pressure from a variable capacity compressor is introduced not only into a first intermediate pressure region, but also into a second intermediate pressure region, thereby making it possible to effectively utilize also a difference in pressure between a high discharge pressure and an intermediate pressure.
The present invention has been made under the circumstances mentioned above, and therefore an object of the present invention is to provide a control valve for a variable capacity compressor, wherein a discharge pressure from a variable capacity compressor is introduced not only into a first intermediate pressure region, but also into a second intermediate pressure region, thereby making it possible to effectively utilize also a difference in pressure between a high discharge pressure and an intermediate pressure.
With a view to achieve the aforementioned object, the present invention provides a control valve for a variable capacity compressor, which essentially comprises a solenoid magnetization portion disposed at a central portion, a main body disposed on one side of said solenoid magnetization portion, and a pressure sensitive portion disposed on the other side of said solenoid magnetization portion, wherein said main body comprises a discharge coolant port communicating with a discharge pressure region of said variable capacity compressor, a first intermediate coolant port communicating with a first intermediate pressure region, a suction coolant port communicating with a suction pressure region, and additionally, a second intermediate coolant port communicating with a second intermediate pressure region of said variable capacity compressor.
According to the control valve for a variable capacity compressor of the present invention, it is possible to introduce a high discharge pressure Pd into a second intermediate pressure region, thereby making it possible to reliably respond to the demand for the effective utilization of not only a pressure difference between the high discharge pressure Pd and the first intermediate pressure Pc but also a pressure difference between the high discharge pressure Pd and the second intermediate pressure Pcxe2x80x2.
According to a preferable embodiment of the control valve for a variable capacity compressor of the present invention, said main body comprises a first valve for opening or closing said discharge coolant port and said first intermediate coolant port, and a second valve for opening or closing said discharge pressure region and said second intermediate coolant port. According to another preferable embodiment of the control valve for a variable capacity compressor of the present invention, said second valve is designed such that said second valve is capable of closing said discharge pressure region and said second intermediate coolant port before said discharge coolant port and said first intermediate coolant port are closed by said first valve.
According to a further preferable embodiment of the control valve for a variable capacity compressor of the present invention, it further comprises a valve chamber having a valve bore at the bottom surface thereof, wherein said first valve is disposed inside said valve chamber and is designed to be actuated by a plunger of said solenoid magnetization portion, and said second valve is actuated following the movement of said plunger.